I feel that eyeliner is the most daunting product to pick out and use for people just starting out with makeup. Everyone has an eyeliner type that is the best for them, there are 5 main kinds of eyeliner; Gel, Pencil, Pen/Felt Tip, Liquid & Powder Eye Shadow. (Keep in mind that all the products I show have been used and loved for months, so they are not in their best condition)
If an angled eyeliner brush is your preferred style of eyeliner application and you are looking for a crisp, clean line, than gel eyeliner may be right for you. I typically wouldn't advise gel liner for beginners, because it takes practice, but some people are good with this type right away. I would also stay away from gel liner if you don't have a lot of time to do your makeup, as this style of liner tends to take longer to do. Gel eyeliner comes in a small pot with a lid and comes in a variety of color, but darker colors are more common and easily accessible.
Even if you decide that a pencil liner isn't the best choice for you for the lid, I think a pencil liner is a must for lining the waterline and if you want, the tightline. Typically, pencil liner creates a softer line than liquid or pen and can look more natural. I like a pencil liner that is soft, so it doesn't hurt your lids, but not too soft where you are constantly sharpening it. I think the Rimmel Scandaleyes liner is a nice halfway between the two extremes. It is a pretty soft liner, but you don't need to sharpen it all the time.
Pen/Felt Tip Eyeliner
I think that the Pen/Felt Tip Eyeliner is a great style of eyeliner for beginners. It allows the precision of a pencil eyeliner without dragging or pulling on your eyelid. I also find that it can be easier than liquid liner. The only downside of these for me, is that these liners dry up faster than liquid and the tip of the liner also dries out quickly.
Liquid Eyeliner is intimidating to a lot of people, but it is my go-to style for a simple line on my lid. I like liquid liner because it doesn't pull on your lid at all and creates a crisp line. This style is easy for some and difficult for others, so I would pick up a cheap one (like the NYC Liquid Eyeliner) to play around with to see if liquid liner is the right thing for you.
Last is the most simple liner style, that I feel is the easiest for beginners. Plus, if you have the desired liner shade you want in a powder eye shadow, then you don't even need to buy an eyeliner! I like to use powder eye shadow for lining my eyes because it gives a much softer, natural look even when you use very dark colors. I also find that it is the most foolproof method since powder is the easiest to rub off out of the 5 styles I have talked about. All I do is take an angled liner brush (or any liner brush style that you like) press it into the shadow and make my line the desired thickness using short strokes. My favorite shadow to use as eyeliner is Blackout (Naked 2) or Crave (Naked Basics) by Urban Decay because it is a very black color and applies effortlessly!